K. Smeets (Karen)http://repub.eur.nl/ppl/22220/
List of Publicationsenhttp://repub.eur.nl/eur_signature.pnghttp://repub.eur.nl/
RePub, Erasmus University RepositoryLiver X receptors regulate cholesterol homeostasis in oligodendrocyteshttp://repub.eur.nl/pub/34783/
Sun, 01 Jan 2012 00:00:01 GMT<div>K. Nelissen</div><div>M. Mulder</div><div>I. Smets</div><div>S. Timmermans</div><div>K. Smeets</div><div>M. Ameloot</div><div>J.J.A. Hendriks</div>
Cholesterol synthesis and transport in oligodendrocytes are essential for optimal myelination and remyelination in pathological conditions such as multiple sclerosis. However, little is known about cholesterol homeostasis in the myelin-forming oligodendrocytes. Liver X receptors (LXRs) are nuclear oxysterol receptors that regulate genes involved in cholesterol homeostasis and may therefore play an important role in de- and remyelination. We investigated whether LXRs regulate cholesterol homeostasis in oligodendrocytes. mRNA expression of genes encoding LXR-α and LXR-β and their target genes (ABCA1, ABCG1, ABCG4, apoE, and LDLR) was detected in oligodendrocytes derived from both neonatal and adult rats using quantitative real-time PCR. The expression of LXR-β and several target genes was increased during oligodendrocyte differentiation. We further demonstrated that treatment of primary neonatal rat oligodendrocytes with the synthetic LXR agonist T0901317 induced the expression of several established LXR target genes, including ABCA1, ABCG1, apoE, and LDLR. Treatment of oligodendrocytes with T0901317 resulted in an enhanced cholesterol efflux in the presence of apolipoprotein A-I or high-density lipoprotein particles. These data show that LXRs are involved in regulating cholesterol homeostasis in oligodendrocytes. Selection of reference genes for gene expression studies in rat oligodendrocytes using quantitative real time PCRhttp://repub.eur.nl/pub/19941/
Mon, 01 Mar 2010 00:00:01 GMT<div>K. Nelissen</div><div>K. Smeets</div><div>M. Mulder</div><div>J.J. Hendriks</div><div>M. Ameloot</div>
Quantitative real time polymerase chain reaction (qPCR) has become a widely used tool to examine gene expression levels. Reliable quantification, however, depends on a proper normalization strategy. Normalization with multiple reference genes is becoming the standard, although the most suitable reference genes depend on the applied treatment as well as the tissue or cell type studied. In this study the stability of various reference genes was investigated in cultures of oligodendrocytes derived from either mature or neonatal rats, the latter also in the presence of the liver X receptor (LXR) agonist.The expression stability of ten commonly used reference genes (HPRT, GAPDH, 18S, ActB, CycA, Tbp, Rpl13A, YWHAZ, HMBS, Pgk1) was analyzed using geNorm and NormFinder. When comparing the different types of cell cultures, Rpl13A, CycA, Pgk1 and YWHAZ were identified as most stable genes. After LXR agonist treatment, CycA, Pgk1 and Rpl13A were found to be the most stable by both geNorm and NormFinder. HMBS and the commonly used housekeeping genes GAPDH and 18S turned out to be the most variable according to geNorm and NormFinder. In conclusion, the use of multiple reference genes, instead of only one, in qPCR experiments with rat oligodendrocytes is strongly advised and standard housekeeping genes such as GAPDH and 18S are not recommended as they appear to be relatively unstable under the experimental conditions used. Reference gene selection should always be performed for each individual experiment, since useful reference genes are very specific for every situation.